Anti-adhesion composition

The purpose of the present invention is to provide an anti-adhesion material having a high anti-adhesion effect. The present invention pertains to an anti-adhesion material comprising a biocompatible sponge-like layered body having a sponge-like first layer and a sponge-like second layer both being at least partially crosslinked with a curing agent and comprising a monovalent metal salt of low endotoxin alginic acid. The monovalent metal salt of alginic acid in the first layer has a weight average molecular weight of 30000 to 300000. The monovalent metal salt of alginic acid in the second layer has a weight average molecular weight of 1000 to 200000. The weight average molecular weights are determined by GPC-MALS after a de-crosslinking treatment. The weight average molecular weight of the monovalent metal salt of alginic acid in the first layer is higher than the weight average molecular weight of the monovalent metal salt of alginic acid in the second layer.